A Graphical User Interface (GUI) has been developed to solve the Falkner-Skan equation. This famous nonlinear third order Falkner-Skan equation on infinite interval describes several fluid dynamic problems under varying the value of two constant coefficients. The developed GUI enables the user to input these two coefficients, which will characterize the behavior of the corresponding solution, and the parameters necessary for the iterative method used to solve the equation. At this regard, a shooting method developed by Zhang J. and Chen B. has been adopted. The required parameters for the numerical solution are represented by the initial shooting angle, the initial free boundary and two tolerance criteria.

Javier,
actualkly there is no variable called a0. Pobably you refer to the variable Alfa0. This is the initial guess for the shooting angle, namely the value of the second derivative at time 0.
I hope I answer to your question.
Giacomo